1. Field of Invention
The invention relates to electrical connectors.
2. Discussion of Related Art
Electrical connectors are used to provide a separable path for electric current to flow between components of an electrical system. In many applications, numerous connections between components can, in turn, require numerous data and/or power connections within a given electrical connector. Lately, there has been increase in the number of connections required for typical electronic components, which in turn has created a demand for greater numbers of electrical connections in electrical connectors. There has also been a general reduction in the size of electronic components, which has created demand for smaller electrical connectors. For either of these reasons, there is a need for electrical connectors with increased current density, where “current density” refers to the amount of current passed through a given connector divided by the area of the connector. By way of example, there is a current demand for connectors that can mate with circular pins that are between 0.050″ and 0.020″ in diameter (or square pins with edges of similar cross sectional length) that are spaced from one another on a pitch between 0.15″ and 0.05″. Some of these electrical connectors are required to handle as much as 5 to 20 amps per connection within the connector. Existing technologies cannot meet these requirements while also providing reliable electrical connections.
The applicant also appreciates that in many applications, particularly those involving small conductors, it can be desirable to maximize the contact area between a conductor and a mating element. Connectors with conductors that make contact over a larger area or that produce multiple contact points per connection can often support greater amounts of current flowing through the connector, and in doing so can provide connectors that can support an increased current density.
Greater contact forces can provide for a more reliable electrical connection by preventing separation of the conductor and mating element. Additionally, higher normal contact forces can cause wiping action between the conductor and the mating element when they are engaged in a sliding manner. This wiping action can help remove debris that might be on the conductor or mating element, which might otherwise reduce the reliability of the connection. Wiping action can also help break oxide layers that can limit conductivity. However, there can be drawbacks to high normal contact forces. Higher contact forces can substantially increase the insertion force required to engage the connector with the mating surface. An operator, attempting to overcome such high insertion forces, may damage the connector. Additionally, the wiping action associated with higher contact forces can cause wear of the conductor and/or mating surface, including removal of desirable coatings, which can lead to oxidation and poor electrical connections.
Electrical connectors are known to use conductors that are displaced under an elastic load during engagement with a mating surface to provide contact forces. However, applicant appreciates that requiring the conductor to be optimized for both transmitting a current and applying a contact force in this manner often requires compromises to be made when choosing materials or configurations for conductors. By way of example, applicant appreciates that high conductivity copper alloys, which have desirable electrical properties, are avoided for use in electrical connectors because of stress relaxation and creep that may occur over time or repeated use. High conductivity copper alloy, as the term is used herein, refers to alloys that have at least 90% of the conductivity of metals made of 99.99% copper. Attempts to improve the mechanical properties of copper with small quantities of alloying agent, such as 0.5% Beryllium, can reduce the conductivity of the alloy to as low as 20% of the conductivity of pure copper.